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Press release

Vaccine Against Leishmaniasis

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Scientists develop vaccination against a parasitic infectious disease

In cooperation with an international research team, scientists at the Charité – Universitätsmedizin Berlin have developed a vaccine that protects against leishmaniasis, a global infectious disease occurring in humans and animals caused by single-cell parasites of the genus Leishmania. The results of the study have been published in the recent edition of the professional journal Science Translational Medicine*.

Leishmaniases are a group of parasitic infectious disease, which are transmitted by sand flies. The affected geographical regions include tropical and subtropical zones, the Mediterranean basin, as well as certain areas of Asia. Approximately two million people are infected each year. The pathogens live in the cells of their hosts, which protects them from being attacked by the 'key players' of the host's immune system - the antibodies. The development of a vaccination against leishmaniasis has proved very difficult to date, largely because the mode of action of most vaccines is to inactivate the pathogens with the help of antibodies.

In the present study, the scientists were able to demonstrate that immunity against leishmaniasis depends on T cells rather than by antibodies. T cells belong to the white blood cells and, like antibodies, are also components of the immune system. Whenever a cell is attacked by a pathogen it transports fragments of the intruder's proteins to its surface. These fragments are detected by the T cells, which destroy the diseased cell together with its intruder. "The efficacy of the newly developed vaccination against the leishmaniasis parasite is based on the activation of T cells, while conventional vaccination techniques have generally relied on antibodies", says Prof. Peter Walden, Head of the Tumor Immunology Research Group of Charité's Department of Dermatology, Venereology and Allergology.

The scientists initially analyzed the genetic material of different antigens in various species of leishmaniasis parasites of different endemic regions. They then examined the reactions of T cells in the blood of patients who were able to overcome the infection against these antigens. Based on the data obtained from both analyses, the researchers then developed effective antigens for the vaccine. "Our goal was to filter out antigens for the vaccine that are not varies in the leishmaniasis parasites and that are able to effectively trigger T cell reactions in the infected individuals", explained Prof. Walden.

The tolerability and efficacy of the vaccine was initially demonstrated in mice. Clinical studies are now planned as the next step in this project. If the vaccine is also effective in humans, it may bring about a fundamental change in the way scientists approach vaccine development.